The Effects of Rock Glacier Meltwater on Thermal Regimes and Nutrient Characteristics in Alpine Lakes in the Uinta Mountains, USA: Preliminary Findings

Climate-induced warming represents a significant threat to alpine lakes, including rock glacier lakes. Warming temperatures increase the melt rate of rock glaciers, increasing the relative hydrological contribution of meltwater to adjacent lakes and streams. Our research focuses on the following question: How have warming-induced meltwater contributions from adjacent rock glaciers impacted the thermal regime and nutrient characteristics of lakes in the Uinta Mountains, USA? To investigate this, we analyzed sedimentary chlorophyll a and changes in diatom community composition in a ²¹⁰Pb-dated sediment core from Gail Lake, a rock-glacier adjacent lake in Uinta Mountains, to infer environmental changes over the last several centuries. Our research indicates that despite enhanced nitrate loading from meltwater, evidenced by the dominance of Asterionella formosa in the uppermost sediments, rock glacier lakes have not experienced concomitant increases in contemporary primary production. Moreover, we find that rock glacier lakes are predominantly characterized by low water clarity and a shallow mixed layer, evidenced by the presence of Discostella stelligera throughout these sediment cores. We suggest that while rock glacier meltwater increases the availability of nitrate, it simultaneously contributes to cold, turbid lake conditions that limit primary production. Our research advances understandings of the effects of rock glacier meltwaters on alpine lake ecosystems at a critical time, as warming increases the hydrological impact of rock glaciers on alpine catchments around the world.

Presentation Preference: Poster

Primary Presenter: Chad Dickson, University of Western Ontario (cdicks26@uwo.ca)

Authors:

Katrina Eyvindson, LARS Research Facility, University of Western Ontario  (katrina.eyvindson@uwo.ca)

John Smol, Paleoecological Environmental Assessment and Research Lab, Queen's University  (john.smol@queensu.ca)